The solar module 100 shown in FIG. 9 is disclosed in Patent Document 1. The solar module 100 is provided with a plurality of solar cells 101. A transparent substrate 102 is arranged on the light-receiving surface side of the solar cells 101. A back sheet 103 is arranged on the back surface side of the solar cells 101. A resin sealing layer 104 fills space between the back sheet 103 and the transparent substrate 102. A low-refraction layer 105 having a refractive index lower than that of the resin sealing layer 104 is provided between the transparent substrate 102 and the resin sealing layer 104. The low-refraction layer 105 protrudes towards the side of the back sheet 103.
Patent Document 1 describes how power generating efficiency can be increased by providing a low-refraction layer 105 to direct light incident between adjacent solar cells 101 towards the light-receiving surfaces 101a of the solar cells 101.